Conservation genomics of an exploited, popular aquarium trade species: the giant Caribbean sea anemone Condylactis gigantea (Anthozoa: Actiniidae)

The marine aquarium trade in the United States operates primarily in Florida, and though the trade’s effects on many marine taxa are largely unknown, local declines have been observed for some harvested species. To reverse local declines in the abundance of the giant Caribbean sea anemone Condylactis gigantea , state managers prohibited harvest of this popular aquarium organism in late 2012. To assess the recovery of C. gigantea following the moratorium, we monitored relative abundance at 45 fixed locations in South Florida from 2013 to 2016. Seventeen of the sites were locations provided to us by commercial aquarium-trade collectors. The remaining sites were locations at which C. gigantea was presumably not being exploited. We found increased densities at only 4 of those 17 sites, while densities at the remaining sites remained unchanged. We also examined genome-wide single nucleotide polymorphism data to assess genetic diversity and population structure of 82 individuals from seven locations (three collection and four non-collection locations) across South Florida. Observed genetic diversity was comparable in all locations. But the location in the eastern Gulf of Mexico showed a significant F IS value, suggesting inbreeding that might be attributed to a small number of occupants. Condylactis gigantea is generally well mixed across South Florida, though a relatively weak pattern of genetic differentiation was detected. These results suggest limited reproductive success and dispersal that is restricted by hydrological and geographical barriers. We highlight the importance of periodic population and genetic monitoring to assess changes in relative abundance and genetic diversity.